The present invention generally relates to inkjet printheads. More particularly, the present invention relates to low-profile inkjet printheads having a contact circuit disposed in a substantially horizontal orientation, such as on a top face of the printhead.
Inkjet printing is a conventional technique by which printing is normally accomplished without contact between the printing apparatus and the substrate, or medium, on which the desired print characters are deposited. Conventional inkjet printing devices such as a fax, printer, photo-printer, all-in-one device, plotter, or any other device incorporating inkjet printing technology typically include one or more printheads in which ink is stored. Such printheads generally are placed within a movable print carriage of the inkjet device. An image is produced by emitting ink drops from an inkjet printhead at precise moments such that they impact a print medium at a desired location. A microprocessor or other controller causes the carriage to reciprocate relative to an advancing print medium and the printhead to emit ink drops at such times corresponding to a pattern of pixels of the image being printed. Such printing is accomplished by ejecting ink from the inkjet printhead of the printing device via numerous methods which employ, for example, pressurized nozzles, electrostatic fields, piezo-electric elements and/or heaters for vapor phase bubble formation.
By way of example, in a thermal inkjet printhead, the ink drops are ejected from individual nozzles by localized heating. The thermal inkjet printhead includes access to a local or remote supply of color or mono ink, a heater chip, a nozzle or orifice plate attached to the heater chip, and a contact circuit in electrical communication with the heater chip. This contact circuit is configured to electrically connect the heater chip to the external device (i.e. a printer) during use. It generally includes input/output connectors (i.e., contacts) that mate with corresponding input/output connectors located on the printer carriage to form an electrical connection between the heater chip and printer. In general, the contact circuit and heater chip comprise a tape automated bond (“TAB”) circuit that is attached to the printhead such that the contact circuit is bonded to a side wall of the printhead such that input/output connectors of the printhead are in a vertical orientation and the heater chip is bonded to a portion of a bottom face of the printhead.
To install these printheads, a user generally must push the printhead into the carriage and then either snap the printhead upward or downward into its locked position within the carriage. When the printhead is properly installed, its vertical input/output connectors mate and form an electrical connection with the vertical input/output connectors of the printer carriage. However, due to the multiple direction movement required to connect conventional printheads to a carriage, users are many times unable to completely and properly form the necessary vertical pressure contact connection, thus causing improper printing. It is desirable to have an improved pressure contact electrical connection.
Due to the area required for the contact circuit (in order to provide sufficient electrical contact) and the placement of the contact circuit on the printhead's vertical side face, conventional printheads have had relatively large height profiles. This height profile has limited manufacturers' ability to decrease the height of printers (i.e. minimum printer height was constrained by height of printhead). In addition, this additional height (i.e., additional materials) of the printhead and printer increases the costs to make the printheads and printers due to the additional materials. Also, the additional height increases the weight of the printhead and printer, thus increasing the packaging and shipping costs.
The printheads have a high center of gravity, which requires printer manufacturers to place limits on the speed of the printer carriage and the number of printheads that can be placed in the carriage in order to prevent printer instability at higher carriage speeds. Limiting the number of printheads has prevented manufacturers from providing more printhead and color combination options. Accordingly, there is a need for improved inkjet printheads.